Time Zones

Your cell phone gets the correct time because it gets the time from the nearby tower, and that tower is configured with the appropriate time zone. In contrast, your GPS unit calculates position and time from satellites in orbit. The problem is that the boundaries between time zones don't follow along longitudinal lines. So while it certainly seems like your GPS unit should be able to determine the time zone it is in, actually programming the GPS software to do it is a non-trivial problem.

Furthermore, GPS units are becoming more and more powerful in terms of their computing power, but they still have only so much memory on board.

As I recall, there's a relatively small area near Tuba City that follows DST while the rest of the state does not. If I can locate the link that describes the area in question, I'll send it to you off line.

I remember on our 1st trip to the Grand Canyon and we had opted to take the less traveled roads across northern Arizona and it seemed that every time we stopped, my watch was always 1 hour off from what I had just set it to at the last stop!

Arizona follows Mountain Standard Time at all times and in all places--except the on the Navajo Nation, which observes Mountain Time (Standard or Daylight as appropriate). So in winter, all of AZ is the same (and corresponds to Denver Time, if you want to think that way). In summer, think of AZ on Los Angeles Time unless you're on Navajo land. Of course, Hopi land chooses to stick with the majority of the Standard Time state even though they're totally surrounded by the Daylight Time summer Navajos.

http://www.kstrom.net/isk/maps/az/navhopi.html

http://www.lapahie.com/Navajo_Map_Lg.cfm
(and note that within Hopi, there's a small Navajo Nation area!)

To make matters slightly worse, for areas around the North Rim of the Grand Canyon (which is always Standard Time) the cell phone signals arise either from Utah or Navajo lands so cell phones incorrectly identify local time as Daylight Time in the summer--which causes quite the issue for dinner reservations at the North Rim Lodge for folks who ignore their watch and believe their cell phone.

Yep, that's why I said this where it starts to get complicated! Thank CraigW for the links.

that was a lot of work.

I use my GPSr for getting from point A to point B - not to tell me what time it is. I have a wristwatch, a cellphone and a clock in my car to tell me the time. The roads don't change when you cross into a new timezone.

My StreetPilot 2720 does not automatically change time zones. My Nuvi 755 does not really have time zones: it just has automatic time.

What I find I want is that the destination time be what the time will be when I get there and I want to know that right from the git go.

On the 2720, I just change to the destination's time zone at the start of navigation. On the 755, it seems to automatically use the destination's time.

The clock is a different matter. Most of us have clocks everywhere. Wanting the GPS to display the correct time at all times is different from wanting to know the arrival time from the git go. In other words, I do not want them synchronized.

I would like the clock to be the current time wherever I am and the arrival time to what it will be when I get there. That all seems to work on the 755.

On the 2720, I have to choose the time zone making either the clock or the arrival time "wrong" when I am not in the destination time zone.

I cannot imagine why crossing a time zone boundary would trigger me wanting to know the new arrival time. I want to know it at all times especially if I want to convey it to people I am hoping to meet up with there or think about traffic or shopping or lodging or eating there.

If we are lucky, automatic current and destination time will become the standard for all GPSs.

Once when traveling east, I lost my motel reservation by arriving after 7 PM because I didn't realize I had crossed into a different time zone. Yeah, I know I should have planned better so I would have known, but I screwed up. So an alert when I crossed time zones would have been a nice reminder to call the motel about arriving late. This happened before the days of GPS. I don't think it will happen now that I have my 755T.

Then why open the thread and make any comments. Just delete it and go on.

just came across this thread
very handy
thanks!

MY Garmin Nuvi 780 will auto update this feature if you have MSN Direct...

Here are the points along the Maine border with Canada where the time zone changes:

-68.32854, 47.360208, Bridge Ave, Time Zone Change

-67.930356, 47.159803, Bridge St, Time Zone Change

-67.789485, 47.060435, Hwy 218, Time Zone Change

-67.789515, 46.92458, Hwy 229, Time Zone Change

-67.789743, 46.824746, Russell Rd, Time Zone Change

-67.789751, 46.793348, Aroostook Falls Rd, Time Zone Change

-67.789381, 46.765315, Main St, Time Zone Change

-67.788402, 46.600321, Riviere des Chu Rd, Time Zone Change

-67.787517, 46.569176, Knoxford Rd, Time Zone Change

-67.784794, 46.450393, Boundary Line Rd, Time Zone Change

-67.781163, 46.135624, I-95 SB, Time Zone Change

-67.781163, 46.134923, I-95 NB, Time Zone Change

-67.780363, 45.816741, Boundary Rd, Time Zone Change

-67.728294, 45.663115, East Grand Lake Rd, Time Zone Change

-67.428653, 45.568704, Hwy 6, Time Zone Change

-67.296817, 45.170089, North St, Time Zone Change

-67.283624, 45.191893, Main St, Time Zone Change

-66.979788, 44.859517, Hwy 189 Time Zone Change

I have a new file in the moderation queue that needs to be uploaded in place of the old one located here: http://www.poi-factory.com/node/6652 Once I get in contact with the file manager this swap will take place.

Miss POI

Would it be better if one deleted the Arizona time zones and made it a separate file with its own mp3 notification and a Navajo file with separate notification and the same for Hopi reservation.
Arizona and Hopi would notify that they do not have DST and Navajo does have DST

The way I would use this file is when I'm driving cross-country and wanted a reminder that I'm passing a time zone. It would be up to me to turn my clock forward or back. Cell phones are great in this regard, once you're far enough into the area, you'll know what time it is.

Arizona tosses in this kink where you have to know which time of the year it since in the summer months Arizona is the same as California and in the winter it is the same as New Mexico (I think I got that right).

As for making the Najavo and Hopi Nations a separate file, my opinion is to include it in the master file. For those on I-40, technically the time doesn't change at the NM-AZ state line but about 10 miles west at Sanders where the highway crosses the Navajo Nation.

Traveling from NM towards the Grand Canyon on Hwy 264 is a different matter. The simple thing would be to leave your watch in New Mexico and not worry what time it was until you got to your destination. I have to think that those who live in that area must be very flexible about what time it is.

If Miss POI will permit... This reminds me of a story where an old Chief was commenting on Daylight Saving Time and said, "Only the white man thinks that by cutting a foot off the bottom of the blanket and sewing it to the top he will make the blanket longer." That Chief must have lived in NE Arizona!

Liked the story about the Chief and daylite savings time. Bob Dee your slipping with the sounds. No sound from this POI.

I can contribute the time zone boundaries around the Navajo & Hopi. What I'll do is use MS Streets & Trips, which shows the boundaries for most reservations, and identify the spots where roads enter the reservation.

I'll send an update when I'm finished.

-Dave

This might help:

http://www.lapahie.com/Navajo_Map_Lg.cfm

It is a fairly detailed map of the region with the boundaries of the Navajo and Hopi Nations and all the roads that cross that land. You might be able to correlate this with what you find on MS S&T.

Here's a couple of points that might help you get started:

-110.000677, 35.763022, AZ-264, Time Zone Change
-110.104397, 35.733185, AZ-264, Time Zone Change

These are for the highway crossings between Alaska and Canada where there is a time zone change.

-141.00214, 62.615669, Hwy 2 - Alaskan Hwy, Time Zone Change

-141.00228, 64.085505, Hwy 5 - Taylor Hwy, Time Zone Change

-136.364426, 59.452268, Hwy 7 - Haines Hwy, Time Zone Change

-135.158516, 59.636159, Klondike Hwy, Time Zone Change

-130.030103, 55.910409, International St, Time Zone Change

Thanks - the reservation boundaries on MS S&T match the boundaries from the website. It even includes the Navajo enclave within the Hopi land (which itself is surrounded by Navajo).

-Dave

The Time Zone boundary in SW Texas is the east Hudspeth County line from New Mexico to the border with Mexico. Both Hudspeth and El Paso Counties are in the Mountain Time Zone.

These points should be deleted:
-105.48298, 31.78066, Ranch Rd 2317
-106.26823, 31.80919, Hwy 375_105
-106.39877, 31.94691, NS Fwy
-106.60157, 31.92525, Hwy 20_104

These points should be added:
-104.916655, 31.763829, US-62
-104.908924, 31.042237, I-10 EB
-104.908924, 31.042362, I-10 WB
-104.908927, 31.037493, Southern Pacific Rd (runs parallel to RR)
-104.908927, 31.036410, Green River Rd
-104.907360, 30.936428, Green River Rd

It must have been that extra brew I had while watching TRI NATIONS RUGBY on the dish. I updated my file with the Alaska, Texas and Maine coordinates at http://latvietislatvija.com/Time_zones_USA.txt.
With football starting, I am going to have to bring the upstairs dish downstairs and irritate my wife.

The 7X5 models automatically take care of changing time zones, according to Garmin.

Supposedly they will give you the correct time of ETA.

Again, according to Garmin.

I have never found an ETA on my 755. There is an estimated time to destination in hours, minutes and seconds but that doesn't have anything to do with time zones. Where is ETA on the 7x5 series?

Let's think about this. The GPSr knows where you are and which direction you are traveling. The internal map database could include time zone boundaries. The software could have a routine that recognizes a TZ boundary and then branches to a set of rules to determine if it needs to adjust the the Time of Day Clock (TOD) forward or backwards based on direction of travel. A companion set of instructions would have to take into account areas that don't follow Daylight Savings Time (DST) and the manufacturer would have to provide a way to update the device's software as needed to take into account the dates when DST starts and ends as that seems to fluctuate here in the US whenever Congress gets a notion to do so.

You now create a route from Amarillo to Albuquerque and the calculated travel time is 5 hours and you depart at 1PM. If this is done correctly, the GPSr should be able to display 2 times when you depart Amarillo: Estimated Travel Time (ETT) = 5 hours and Estimated Time of Arrival (ETA) for local time at destination = 5PM (1PM + 5 hours - 1 hour for crossing one time zone going west). As you physically cross the TZ line, the GPSr would then update its TOD to correctly display the local time. As you travel, the ETT and ETA would adjust accordingly if you were making better or worse time than 1st calculated - just as most GPSr have been doing all along.

I believe some of the newer nüvi models are capable of factoring in time zones, but I haven't had hands on one yet to see for myself. Arguably, there are some who could care less if their GPSr could do these things and there are those who would like to have it. That's why there's so many models to choose from. I am just surprised that it has taken Garmin this long to offer this feature.

Has Miss POI added you as a maintainer for this file? If so, you can update it directly at http://www.poi-factory.com/node/6652 I think she was looking into this for you, but may have other things in the queue ahead of this.

Did you see the corrections I listed on 9/15 for the area around El Paso?

After creating a route on the 750, it displays the ETA in the lower left corner of the screen. If I touch the green bar at the top of the screen and then the Show Map button on the bottom, it displays the Estimated Travel Time.

In browsing this page: http://home.comcast.net/~ghayman3/garmin.gps/page7x5.01.htm#... it does appear that the 755(T) will display both ETA and ETT. How it implements the ETA with the time zone change is something I'm not familiar with as the 750 can't do any of that.

Thanks TXRVer. Talk about a "senior moment", I looked for ETA many times and couldn't find it. I didn't notice that there are scroll arrows on the selection screen ... actually ETA is the first choice and mine was defaulted to the bottom of the list. So all I had to do is scroll up to the top of the list. DOH! Now I can experiment to see how the time zones affect the ETA.

I'd be interested in hearing how or even if Garmin implemented the complex time zones in NE Arizona.

Leaving Gallup NM going north on US 666 and then turning west on Hwy 68 will take you to the NM-AZ state line where Hwy 68 becomes Hwy 264. Two things occur here:

1st, Arizona doesn't observe DST so part of the year AZ keeps time with California and the rest of the year it is the same as NM.

2nd, Hwy 264 in Arizona is within the Navajo Nation which does observe DST! As you continue west, you will enter the Hopi Nation which is completely within the boundaries of the Navajo Nation. The Hopi follow the custom of Arizona and do not observe DST... And within the Hopi Nation, Hwy 264 bisects a small island of Navajo land encompassing the communities of Jedito and Keams Canyon within the Hopi land. Hwy 264 then exits the Hopi Nation and ends near Tuba City where US 64 or Hwy 89 continues west or south, exiting the Navajo Nation. At these points you are in Mountain Standard Time.

This must be a place where life is simpler and little is governed by the clock.

Don't see a contact for Drdevo. Has anyone else had a problem with the first line of the Time Zone USA POI file, it is a header line. I am using POI Loader Ver. 2.5.3, and it errors off on the first line.

There should not be a header line. Then after that there are blank lines he has separating states.
You could repair it yourself by opening it excel and removing the errors and resaving for your use, but it should be fixed properly.

Since there is no contact you need to send an email to Miss Poi.
http://www.poi-factory.com/about